The influence of nozzle diameter on the circular hydraulic jump of liquid jet impingement

In this study, the circular hydraulic jump of jet impingement cooling was experimentally investigated using water as the test fluid. The effects of nozzle diameter (0.381, 0.506, 1, 2, 3.9, 6.7, 8 mm) on the hydraulic jump radius were considered. The results indicate that the dimensionless hydraulic jump radius (r(hj)/d) is independent of the nozzle diameter under fixed impingement power conditions, while the dimensionless hydraulic jump radius increases with decreasing nozzle diameter under fixed jet Reynolds number conditions. Based on the experimental results, a new correlation for the hydraulic jump radius is proposed as a function of the impingement power alone. It is shown that the proposed empirical correlation for the dimensionless hydraulic jump radius has the same form as that derived from a dimensional analysis of the conservation equations. In addition, the results clearly show that the dimensionless hydraulic jump radius depends on two dimensionless groups, jet Reynolds and Froude numbers, rather than just one, jet Reynolds number. (C) 2015 Elsevier Inc. All rights reserved.